Last season's player of the year Ryan Stott scored four as holders Culter reached the quarter finals by thrashing Newmachar United 8-2 in Section 3.
Chris Craib and Duncan Chalmers netted for Ellon United as they came from behind to win 2-1 at Lewis United and top Section 1, while Maud qualified from Section 4 after Deveronside lost at home to Fraserburgh United.
Tuesday's fixtures will see three other clubs qualify.
Banchory St Ternan will qualify from Section 2 if they can win at East End otherwise Hall Russell United will top the group. Forres Thistle will qualify from Section 6 if they can avoid a three goal defeat to closest rivals Nairn St Ninian at Logie Park, while three clubs can still qualify from Section 7 with Burghead Thistle, Inverness City and New Elgin still in the running. Inverness City and New Elgin meet at Burghead and the winner will reach the last eight, while Burghead will go through if honours are even.